The present invention relates in general to sewing machines and in particular to a new and useful arrangement which utilizes a diode rectifier bridge and a phase controlled rectifier bridge for controlling the speed of a sewing machine motor as well as powering a lamp of the sewing machine which are connected by a three plug connector in the housing of the sewing machine.
For the control of their motor, such sewing machines are generally equipped with a foot starter that contains a resistor. There are also sewing machines which have installed in their housing an electronic phase angle control. The phase angle control is itself controllable through a potentiometer arranged in the respective foot starter. A starter with an ohmic resistor or a starter with built-in phase angle control for controlling the rpm of the sewing machine can thus be selectively connected to the sewing machine only at considerable expense, especially since the usual phase angle control operating with alternating current substantially reduces the maximum attainable speed of the sewing machine.
Replacing a normal impedance starter by one with built-in phase angle control was not successful in particular because using a phase angle control would have required greater expense for line connections to the sewing machine if there was to be no loss of speed as compared with the impedance starter. The task involved in the present invention is therefore, to provide an electronic starter control with which the maximum rpm of the motor which is controllable with the normal impedance starter, can also be reached and where the connection to the sewing machine is feasible without the increased cost of circuitry.